Steam generator with double outlet furnace



March 25, 1952 J. A. I AcERr-:NzA

STEAM GENERATOR WITH DOUBLE OUTLET FURNACE Filed April 22, 1948 2SHEETS-SHEET l P m U 2f 4 M9 w \|V3 4, M4 M a zzm wwwa@ 6 `045 5 5 f WWW7 5 v A 3 0900. s |11 7 \/|M .32m/ 4 0 J. :OJ 5

/9 mlm J. A. LACERENZA March 25, 1952 A STEAM GENERATOR WITH DOUBLEOUTLET FuRNAcE I 2 SHEETS-SHEET 2 Filed April 22, 1948 INVENTOR J. A.Lucerenzo non Fig. 5.V

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ATTORNEY Patented Mar. 25, 1952 GENERATOR WITH DOUBLE OUTLET FURNACEJoseph A. Lacerenza, New York, Ne Y., assignor t0 CombustionEngineeringeuperheater, I nc., a corporation of Delaware ApplicationApril Z2, 1948, Serial No. 22,643

11 Claims. (C1-lmfao This invention relates to improvements in steamgenerators and particularly to steam .generators provided withsuperheaters and reheaters and having improved means for regulating thetemperatures of the steam leaving said heaters.

High capacity steam generators working at high pressures and deliveringsteam at high temperatures may have a major portion or al1 of the steamreturned to be reheated in the steam generator to a high temperature.For example, if the steam is delivered to a steam turbine at atemperature such as'about 950 F. a major portion, such as about 90%, maybe returned from an intermediate stage of the turbine to the steamgenerator to be reheated to a high temperature, such as about 950 F.,`and thence returned to the subsequent stages of the turbine.

When in such a generating plant the superheater and reheater are placedwithin the steam generator in series with respect to the gas flowthrough the generator, and with all of :the gas flow flowing over bothheaters, the reheat temperature will be `too high at the high loads, ifthe reheater is designed to provide the proper temperature at the lowerloads, -or it ywill fbe too low at the low Vloads if the reheater is.designed to provide the proper reheat at 4the higher loads.

To correct these departures from the desired steam temperatures by meansof `by.passir-1g some of the gases around eitherof lthe heaters involvesmore `than necessary heat yabsorbing surface in said respective heatersand additional vheat absorbing surface to reduce the excess `temperatureof the byfpassed gases.

When the superheater and reheater are placed in parallel passes for thefurnace leaving gases, the relative amounts of gas flowing over theheaters may be shifted from `one pass to the other in accordance withthe Vheat requirements of the heaters, whereby the above mentioned ob.-jections may be substantially overcome.

It is an object .of this invention to provide in a highY capacity steam-generator having steam heating surfaces within parallel passes for thefurnace leaving gases, novel arrangementsof fuel burning means and heatabsorbing ysurfaces to more efficiently lregulate the temperature andflow of said gases through said passes for superheating and reheatingvthe steam from the generator Vto its Vproper 4temperatures.

Additional objects of the invention will appear from the followingdescription `of one preferred embodiment of the invention when taken inconjunction with the accompanying drawings wherein: c

Figure 1 is a diagrammatic vertical section through a steam generatorembedying the lne vention.;

Figure 2 is a cross section teken Yon line 2-2 of Figure v.1;

Figure@ is a cross section taker 91.1 lille 3f? of .Figure 1; and.

Figure e .is a fragmentary vertical section through e typical burner 0fthe tilting tyre,-

\ Figure .5 is a diagrammatic illustration af e vsurerheeter 'with a.desuperheatsr arranged the steam line to the rrirremover esillustratively Shown .ir-1 Figure ,1 my improve@ S''lellll generali@COKlDlSQS a lllllf? Wllll may ,include three generally vleslellelsl esA' .l5 and .C- .At the top of the ,furnace ,1S ,er Outlet U and at thebottom of the furnace another outlet 1.,. The furnace may be providedwith two af A,burners en. upper Set l and e lower ,Set 2. ,Preferablythe burners are of the tilting type as disclosed in the U. S. Patent toKreisinger `et al. No. 12,363,875. The upper set of burners I may bearranged to be tilted independently of the lower set of burners 2. t

Preferably the furnace is completely lined on all sides with steamgenerating tubes 3 which vare connected for circulation of water there,-through to the steam and water drums ,4 and 5 Yvia risers l and 3.Risers 6 and 1 connect respectively the :fr- Ont and rear walls of thefur.- nace to drum 4 while risers 8 connect the Yside wallsthroughyheaders 9; there being two headers 9, one for each side wall. Amultiplicity of downcomer tubes 'l0 connect the steam drums 4 and 5 toheaders lvl and `I2 from which the downfcomer tubes yI3 and l4 carrywater from the drums tothe bottom headers l 5, I6, Il, :L8 and IS Iofthe water walls. There yare similar headers 15 l1 and I9 for the sidewail opposite that shown.

The offtakes U and L direct the gases Aleaving the vfurnace Vinto twopasses -20 and 2l. Upper pass 20 is provided with an outlet -2'2 whileVlower pass 2| is provided with an outlet 23. Preferably said outlets 22and 2-3 are adjacent one another and are provided -wit-h dampers 124 and25 for throttling gas 4flow therethrough.

Preferably the passes 20 and 2 l have-Wallslined with steam generatingtubes connected into circulation with the steam drums 4 and 5. Ad-

Ijacent the offtake U some of the water wall tubes 3 1a extend viarisers 1 into drum 4. The horizontal portions of these risers 1 serve asa support for the roof 21 of the furnace and for the upper end of thepass 20. The remaining of the water wall tubes 3 may pass upwardlyacross offtake U and join risers 1 into the drum 4.

Adjacent the lower oitake L of the furnace some of the water Wall tubes3a rise from header I8 upwardly and rearwardly along the bottom of pass2| thence rise in open formations across the pass, thence extendforwardly toward the furnace while supporting the upper wall of thepass, and thence rise in alignment with the remaining tubes 3 of therear wall of the furnace. The remaining tubes 3a from header I8 risevertically across oitake L and join the former tubes 3 in alignment withthe rear wall of the furnace.

The walls of the vertical portion of passes 2U and 2| are preferablylined with steam generating tubes which are supplied from the bottomheaders I8 and 28. The tubes 29 rising from header 28 extend upwardlyadjacent the front Wall of pass 2| for a short distance, thence some ofthe tubes 29 extend into the pass and upwardly to form a by-pass 30.Above by-pass 30 the tubes 29 adjacent the front wall extend inwardly tojoin the remaining tubes and thence continue upwardly in alignment againalong the front wall of pass 2| and up into pass 20. After passingupwardly for a distance in pass said tubes 29 again spread apart into alower group 3| and an upper group 32 forming the walls of a jby-pass 33.At the upper end of said by-pass 33 the lower group of tubes 3| bendupwardly to cross the by-pass 33 and connect to header 26. lTheydischarge through risers 1a, 1 to the steam drum 4. At the upper end ofsaid by-pass 33 theI upper group of tubes 32 bend upwardly as tubes 32aacross the pass 20 and thence continue to discharge into drum 5.By-passes 3U and 33 are provided with dampers a and 33a.

The rearward sides of passes 2| and 20 are lined with tubes 34 which arecontinuations of tubes 35 rising from header I8 and extending 'acrosspass 2| to the rear wall thereof. Thence 'tubesl 35 continue upwardly astubes 34 through both the passes 2| and 20 and at their upper ends bendforwardly to form the roof tubes 36 of pass 20. The upper ends of saidroof tubes 36 bend upwardly and thence continue astubes 36a into drum 5.

Within the upper portion of pass 20 is a superheater divided into threesections 31, 38 and 39. `Steam from drum 5 is conveyed via tubes 4U intothe superheater inlet header 4| whence it flows lserially throughsections 31, 38 and 39 to superheater outlet header 42.

The superheater sections 31, 38 and 39 may constitute the entiresuperheater surface required.

vShould more superheat be required than can be eiciently provided bythese sections, it may be desirable to locate a further superheatersection -43 within the lower portion of pass 2| which re- -ceives thesteam from outlet header 42 Via con- -nection 44 into its inlet header45. Steam leaves superheater 43 via outlet header 46.

Adjacent said superheater 43 and located within the lower portion ofpass 2| is a portion of a reheater 41 the remaining portion 48 of whichis located within the vertical portion of pass 2|'. Steam from anintermediate expansion stage of a prime mover, such as a steam turbine,is con- 'ducted to the inlet header 49 of the reheater by a conduit notshown, thence passes downwardly rthroug'h'reheater 48 comprising a bankof sinuous tubes and connected to the sinuous tube bank of reheaterportion 41 via tubes 50; Steam leaves the reheater 41 via outlet header5| to be returned to a later stage in said prime mover.

Within the vertical portions of passes 2| and 20 and adjacent theoutlets 23 and 22 thereof is llocated an economizer having lower andupper sections 52 and 53 respectively. Feed water enters the lowerportion of lower economizer section 52 thence flows upwardly through thetubes of the economizer into thelower portion of the upper section 53thence upwardly through that section and out of the top thereof into thedrum 4 through connections not shown.

Figure 2 shows one preferred arrangement of the burners and 2 withrespect to the furnace. located adjacent or at the corners thereof. Thefuel streams issuing from each set of these burners are directedtangentially toward the surface of an imaginary vertically disposedcylinder within the furnace and may selectively be directed upwardly anddownwardly as taught by Kreisinger et al. Patent 2,363,875 earlieridentified.

Referring to Figure l, the groups of burners and 2 are preferablyconnected each group to one mill 54 or mill 55, or sets of separatemills, and the fuel is delivered from the mills through conduits 56, 451to fans 58, 59 and thence via. conduits 68, 6| to the groups of burnersand 2 respectively. Only two mills are shown by way of example, eachconnected to one set of burners. Obviously the remaining burners aresimilarly connected although not so shown. By such grouping of mills andburners, the amount of fuel delivered by burners may be varied from thatdelivered by burners 2 by regulating the fuel output of the respectivemills by controlling the speed of each mill motor MI and M2. In theillustrative embodiment shown in Fig. 1 a speed adjuster SI isinterposed in the line between the power source and mill motor MI.Similarly a speed adjuster S2 is interposed in the line between thepower source and mill motor M2. Each motor drives its respective mill 54or 55 as well yas fan 51 or 58 which delivers the fuel to the burner or2 respectively.

Figure 3 is a plan section through the furnace and the upper pass 2Ushowing the superheater sections 31, 38 and 39 within said pass.Preferably the by-pass 33 extends for the full width of the pass 29, asthis drawing view shows.

Figure 4 shows a typical fragmentary sectional view through one of theburners. It comprises an air casing or housing 62 and pulverized fuelnozzle I, 2 extending therethrough. Only one such fuel nozzle is shownin this disclosure. The

fuel nozzle comprises a conduit 63 which is provided with an end pieceor tip 64 rotatable vertically about horizontal supporting bearings 65on the end of conduit 63. The tip 64 and conduit v63 may be formed attheir juncture to a socket type of joint as shown.

' vSurrounding the nozzle tip 64 and mounted thereon is a tubular airdeflecting vane 66, the whole when tilted upwardly or downwardly,directing the fuel and air stream accordingly into the furnace. The tip64 and vane 66 are rotated by means of a rod 61 connected at one side ofthe tip by an arm 68 fixed to the pin of bearing 65 on which the tip 64rotates. 'Ihe other end of rod 61 is connected to a bell crank 68 whichis yconnected to a vertically movable member 69. Vlhen the verticalmember'89 is moved upwardly or downwardly it tilts the burner eitherdownwardly or'upwardly.

Above and below each of the fuel pipes there are provided air chambers J.having tips 1| which rotate upwardly anddownwardly together with thefuel nozzles 64 and through .the same angularity. The tips 1| arepivoted at 12 and connected by rod 13 to the end of the bell crank 14similar to the bell crank for operating the fuel nozzles, the bell crank14 being lin turn .connected to the vertically movable member 69.

According to the invention the steam generator is .provided with twoparallel passes with respect to the flow of furnace leaving gases, onepass 20 being connected .to an offtake U adjacent one end of the furnaceand the other pass 2| being connected to an offtake D adjacent the otherend of the furnace. One or more heaters are placed within each of thesepasses as already described, the heaters absorbing relatively variableamounts of heat from the gases in order to heat the respective fluidspassing through them to the proper temperatures at the various ratingsof the steam generator. To meet these variations in heat absorption, theamount of gases flowing through each pass 2U and 2| is varied and/or theentering temperature of the gases to each of the passes is varied,supplemented by the control dampers in each of the passes.

The heat in the furnace leaving gases entering each pass 2i) and 2| maybe regulated by varying the amounts of fuel delivered by the variousburners to the furnace. By varying the fuel delivered by the mills 54associated with the upper burners the heat flowing into the upper pass2D with the gases may be varied to suit and by varying the fueldelivered by the mills 55 associated with the lower burners 2, the heatflowing into the lower pass 2| may be varied to suit.

The temperature of the furnace leaving gases may also be varied bytilting the burners by means disclosed in the U. S. patent to HenryKreisinger et al. No. 2,363,875. By tilting the upper burners Iupwardly, the mass of flame therefrom will move into the upper portionof the furnace to zone B and consequently less heat will be absorbedfrom the flame" by the portions of the furnace below the llame resultingin relatively hotter furnace leaving gases to the upper pass 20. Bytilting the lower burners 2 downwardly to zone C the mass of flame fromthe fuel delivered by these burners will move into the lower portion ofthe furnace and less heat will be absorbed from said llame vby theportion of the furnace above the flame, resulting in relatively hotterfurnace leaving gases to the bottom pass. Should the upper pass requiresubstantially more heat both the upper and lower burners may be tiltedupwardly and should it require substantially less heat both the upperand lower burners may be tilted downwardly.

The flow of gases through the respective passes is controlled by dampers24 and 25 to supplement the burner control. Obviously any combination ofangularity of the burners may be used and/or any variations in fuelsupply by the various burners may be used to obtain the desired steamtemperatures of the steam leaving the respective heaters.

The by-passes 3l! and 33 and the regulation of dampers Sila and 33a mayserve to care for minor fluctuations in temperatures not covered by themanipulation of the burners and/or dampers 24 and 25. Furthermoredesuperheating of the steam by means well known, such as desuperheater80 (Fig. l), may be employed to iron out small variations in steamtemperatures leaving the heaters due to heat lag caused by the largemass of metal in the heaters. In the preferred embodiment .of myinvention .shown in Fig. l the desuperheater is arranged betweerstages31 and 38 of the superheater. .In some cases, especially in .cases wherea single :stage superheater is utilized as diagrammatically indicated inFig. 5 a desuperheater 8l is located in the steam line connecting thesuperheater with the turbine. In other cases such as in connection witha reheatsuperheater 4l, 48, Fig. l, a desuperheater 82 is preferablylocated in the steam line between the intermediate expansion stage ofthe steam turbine and the reheater. Each desuperheater 30, 8| vand 82 isconnected to a supply of spray water or cooling fluid (not shown) in amanner well known in the art. f

By advantageously dividing the heaters and placing them within the twoparallel passes with respect to gas flow a relatively lower resistanceto gas flow may be obtained.

Should the resistance to gas flow through the heaters within the twopasses 20 and 2| be materially different, the overall resistances may besubstantially balanced by shifting some of the economizer heatingsurface from the pass of high resistance into the pass of lowresistance.

Should the heat absorption from the gases by the heaters within the twopasses 20 and 2l be materially different, the overall absorption of eachpass may be substantially .balanced by shifting some of the economizerheating surface from the pass of high heater absorption to the one oflow absorption.

By placing the reheater and the second stage of the superheater in thebottom pass both will be located adjacent the operating iloor at a levelnearer the steam turbine which they serve and the superheater connectionto the turbine will involve shorter high pressure and high temperaturepiping.

A further advantage is in having two sets of superimposed burners, theupper set burning one fuel Whose products of combustion rise to ilowinto the upper furnace offtake and pass, and the lower set burninganother fuel whose products of combustion flow downwardly into 'thelower furnace oiftake and pass. In this manner the two flames andproducts of combustion of Athe separate fuels avoid being mixed. Suchmixture may result in slag deposits on lall of the heating surfaces,both upper and lower, if one ofthe fuels contains slag producingelements. By separating the flow of the products of combustion lfromeach fuel according to the invention, the heating surfaces in the pathof the products of combustion from the non-slagging fuel will remainlfree from slag. .For example, such fuels Aas blast furnace gas or oilmay be delivered to the upper set of burners while pulverized coal maybe delivered to the lower set.

While the preferred embodiment of my invention has been shown anddescribed, it will be understood that changes in construction,combination and arrangement of parts may be made without departing fromthe spirit and scope of the invention as claimed.

I claim:

1. In a steam generating unit having a generally vertical furnaceassociated therewith; steam generating tubes lining the walls of thefurnace; a top offtake adjacent the upper end of the furnace and abottom offtake adjacent the lower end of the furnace; means forming twopasses for the flow of furnace leaving gases therethrough, the first ofsaid passes being connected tto said top offtake and the second passbeing connected to said bottom oftake; damper means in.

at least one of said passes adjustable to govern the apportionmentbetween those two passes of the total gases leaving the furnacetherethrough; at least one fluid heater arranged in each of said firstand second passes; burner means located between said top and bottomofftakes in the furnace walls and arranged for delivering fuel and airto be burned into the furnace tangenltially to an imaginary verticallydisposed cylinder in said furnace; and means for tilting said burnersfor directing the fuel and air streams therefrom .withn the furnacetoward said top oiftake or toward said bottom oflltake tov vary therelative amount of heat absorbed by said steam generating tube portionsin both the upper and lower portions of the furnace.

2. In a steamI generating unit having an associated furnace; steamgenerating tubes lining the walls of the furnace; an offtake adjacentone end of the furnace and another offtake adjacent the other end of thefurnace; means forming two passes for the flow of furnace leaving gasestherethrough, the first of said passes being connected to one of saidofftakes and the second pass being connected to the other oiftake;dampers in said passes adjustable to govern the apportionmenttherebetween of the total gases leaving the furnace therethrough; asteam superheater and a steam reheater arranged one in each off saidfirst and second passes; burner means located between said offtakes inthe furnace walls and arranged for delivering fuel and air into thefurnace to be burned therein; and means for tilting said burners fordirecting the fuel and air streams therefrom within the furnace eithertoward one offtake or rtoward the other offtake to vary the relativeamount of heat absorbed by said steam generating tubes located in thatpart of the furnace which is adjacent to said one offtake and that partof the furnace which is adjacent to said other offtake.

3. In a steam generating unit having a generally vertical furnaceassociated ltherewith; steam generating tubes lining the walls of thefurnace; an upper oiftake adjacent the upper end of the furnace andanother lower offtake adjacent the lower end of the furnace; meansforming two passes for the flow of furnace leaving gases therethrough,the first of said passes being connected to the said upper offtakes andthe second pass being connected to the said lower offtake; dampers insaid passes adjustable to govern the apportionment therebetween of thetotal gases leaving the furnace therethrough; a rst stage steamsuperheater arranged in said rst pass and a second stage steamsuperheater plus a steam reheater arranged in said second pass; burnermeans located between said upper and lower offtakes in the furnace wallsand arranged for delivering fuel and air into the rfurnace to be burnedtherein; and means for tilting said burners for directing the fuel andair streams therefrom upwardly within the furnace and toward said upperofftake or downwardly within the furnace and toward said lower offtake,to vary the relative amount of heat absorbed by said steam generatingtube portions in the upper and lower portions of the furnace.

4. In a steam generating unit having an associated furnace; a steam andwater drum; steam generating tubes lining the Awalls of the furnaceconnected for circulation to said drum; an upper oiftake adjacent theupper end of the furnace and another lower otake adjacent the lower.@dei the .www means forming two passes for the flow of furnace leavinggases therethrough, the flrst of said passes being connected to the saidupper offtake and the second pass being connected to the said loweroiftake, the rearward portions of said passes with respect to gas flowtherethrough being in substantial vertical alignment; steam generatingtubes extending through both said rearward pass portions and lining thewalls off said passes and connected for circulation to said drum;dampers in said passes adjustable to govern the apportionmenttherebetween of the total gases leaving the furnace therethrough; atleast one steam superheater arranged in one of those passes and a steamreheater arranged in the other; burner means located between said upperand lower offtakes in the furnace walls and arranged for delivering fueland air into the furnace to be burned therein; and means for tiltingsaid burners for directting the fuel and air streams therefrom upwardlywithin the furnace and toward the upper offtake or downwardly within thefurnace and toward said lower oiftake to vary the relative amount ofheat absorbed by said steam generating tubes in the upper and lowerportions of the furnace.

5. In a steam generating unit having an associated furnace; steamgenerating tubes lining fthe walls of the furnace; an upper oitakeadjacent one end of the furnace and another lower oiftake adjacent theother end of the furnace; means forming two passes for the flow offfurnace leaving gases therethrough, the first of said passes beingconnected to the said upper offtake and the second pass being connectedto the said lower offtake; dampers in said passes adjustable to governthe apportionment therebetween of the total gases leaving the furnacetherethrough; at least one steam superheater arranged in one of fthosepasses and ea, steam reheater arranged in the other; means forming aby-pass for the flow of some of the furnace gas'es around at least oneof said heaters; a damper in said bjr-pass for regulating said ow;burner means located between said two offtakes in the furnace walls andarranged for delivering fuel and air into the furnace to be burnedtherein; and means for tilting said burners for directing the rfuel andair streams therefrom within the furnace upwardly and toward the upperofftake or downwardly and toward the lower offtake to vary the relativeamount of heat absorbed by said steam generating tubes in the upper andlower portions of the furnace.

6. In a steam generating unit having an associated furnace; steamgenerating tubes lining the walls of the ffurnace; a top offtakeadjacent the upper end of the furnace and a bottom offtake adjacent thelower end of the furnace; means forming two passes for the flow offurnace leaving gases therethrough, the first of said passes beingconnected to the said top offtake and the second pass being connected tothe said bottom offtake; dampers in said passes adjustable to govern theapportionment therebetween of the total gases leaving the furnacetherethrough; at least one fluid heater arranged in each of said firstand second passes; upper and lower burner means located between saidupper and lower offtakes in the furnace walls for delivering fuel andair into the furnace to be burned therein; and means for tilting saidupper and lower burners for independently directing Within the furnacethe upper and lower fuel and air streams issuing therefrom upwardly andtowardl 9 said tcp oiftake or downwardly and toward said bottom offtaketo vary the relative amount of heat absorbed by the steaml generatingtube portions adjacent the top offtake and the steam gen- `@rating tubeportions adjacent the bottom 01T- haake;

7. In a steam generating unit having an lassociated furnace; steamgenerating tubes lining l the walls of said furnace; `an offtakeadjacent one end of the furnace and another offtake adjacent the otherend of the furnace; means forming two passes for the flow offurnace-leaving gases therethrough, the first of said passes beingconnected to one of said offtakes and-the second pass .being connectedto the other offtake; damper means in at least one of said passesadjustable to govern the apportionment therebetween of the total gasesleaving the furnace therethrough; at least: one fluid heater arranged ineach of said first and second passes; burner means located between saidofftakes in the furnace walls for delivering air and fuel into thefurnace to be burned therein; and means for tilting said burners fordirecting the fuel and air streams therefrom within the furnacel eilthertoward one offtake or toward the other offtake, to vary the relativeamount of heat yabsorbed by the furnace wall portion adjacent the saidone oiftake and the furnace wall portion adjacent lthe said otherofftake.

8. In a steam generating unit Ihaving an associated furnace; a topofftake adjacent the upper end of the furnace and a bottom offtakeadjacent'the lower end of the furnace; means forming two passes for theflow of furnace-leaving gases therethrough, the first of said passesbeing connected to the said top offtake and the second pass beingconnected to the said bottom offtake; at least one fluid heater arrangedin each of said first and second passes; at least two burners located inthe furnace `walls intermediate said upper and lower offtakes for theredelivering air and fuel streams into the furnace, the aforesaid fuel andair from eaoh individual burner creating a mass of high temperatureburning gas within the furnace interior; individual tilting means foreach of said burners for independently directing the fuel and air streamissuing therefrom eifther upwardly within the furnace and toward saidtop offtake or downwardly within the furnace and toward said bottomofftake so as to bring the location orf each burner-produced mass ofburning gas within the furnace walls either closer to said top oftakeand more remote from said bottom offtake or closer to said bottomofftake and more remote from said top oiftake and, by reason of thevelocity head created by said tilted up or tilted down stream of air andfuel from each burner, to increase the gas pressure adjacent theparticular offtake towards which each burner is tilted and thereby causethe gas flow through that oiftake correspondingly to increase; and steamgenerating tubes lining the walls of said furnace for absorption of heatfrom each of said burner-produced masses of high temperature gas, thequantity of heat so absorbed by said walllining tubes from each of saidburner-produced masses of high temperature gas varying with theveritical location of that gas mass within the furnace whereby theaforesaid tilting of each furnace burner alters the total heat leavingboth the top and the bottom furnace offtakes and varies both thequantity and lthe temperature of the gases leaving said top offtake andof the gases leaving said bottom offtake thereby to control the heatabsorbed by each of the aforesaid uid heaters in said top and bottomoiftake passes` 9. In a steam generating unit having an associatedfurnace; an offtake adjacent one end of the furnacev and another offtakeadjacent the other end ofthe furnace; means forming-two passes for theflow of furnace-leaving gases therethrough, the first of said passesbeing connected to the said one yofftalre and thesecond pass beingconnected to the said other offtake; at least one superheater arrangedin each of said rst and second passes; burner means located in thefurnace walls intermediate said two oiftakes for there delivering intolthe furnace streams of fuel and air creating a mass of high temperatureburning gas within the furnace interior; means for tilting said burnermeans to direct saidfuel and air streams issuing therefrom either towardthe furnaces said one oitake or toward the furnaces said other offtakeso as to bring the location o-f said high temperature nrass of burninggas within the furnace walls either closer to said one offtake and moreremote from the other offtake or closer to said other offtake and moreremote from said one offtake and, by reason of the direction given bysaid burner tilt to the velocity head inherent in said streams of airand fuel from the burner means, to increase the gas pressure adjacentthe particular offtake towards which the burner means is tilted andthereby cause the gas flow through that offtake correspondingly toincrease; steam generating tubes lining the walls of said furnace forabsorption of heat from said mass of high temperature gas, the quantityof heat so absorbed by said wall-lining tubes varying with the locationof said high tem-'- perature gas mass within the furnace along thelength thereof between said one end offtake and said other end offtakewhereby the aforesaid tiltingv of said burner means alters lthe totalheat leaving both the one and the other furnace offtake and varies boththe quantity and the temperature of the gases leaving said one offtakeand of the gases leaving said other offtake thereby to control the heatabsorbed by each of said superheaters in the said one and other oiftakepasses; and desuperheater means associated with at least one orf saidsuperheaters to effect final control in the temperature of steam passedtherethrough.

10. In a steam generating unit having an associated furnace; an offtakeadjacent one end of the furnace and another offtake adjacent the otherend of the furnace; means forming two passes for the flow offurnace-leaving gases therethrough, the rsit of said passes beingconnected to the said one offtake and the second pass being connected tothe said other offtake; at least one fluid heater arranged in each ofsaid first and second passes; burner means located in the furnace wallsintermediate said two offtakes for there delivering into the furnace astream of combustible mixture creating a mass of high temperatureburning gas within the furnace interior; means for tilting said burnermeans to direct said stream of combustible mixture issuing therefromeit'her toward the furnaces said one offtake or toward the furnaces saidAotherl offtake so as to bring the location of said mass of burning gaswithin t-he furnace walls either closer to said one offtake and moreremote [from the other offtake or closer to said other offtake and moreremote from said one offtake land, by reason of the direction given bysaid burner tilt to the velocity head inherent in said stream ofcombustible mixture, to increase the gas pressure adjacent theparticular offtake towards which 1 the burner means is tilted andthereby cause the gas ow through that offtake correspondingly toincrease; means for varying the quantity of the combustible mixturebeing discharged from said tiltable burner means whereby to vary thevelocity head and gas pressure in said gas mass as well as the quantityof gas flowing through each of said oftakes; and steam generating tubeslining the walls of said furnace for absorption of heat from said massof high temperature gas, the quantity of heat so absorbed by saidwall-lining tubes varying with the location of said high temperature gasmass within the furnace along the length thereof between said one endoitake and said other end oiftake whereby the aforesaid tilting of saidburner means alters lthe total heat leaving both the one and otherfurnace oii'takes and varies both the quantity and the temperature ofthe gases leaving said one oitake and of the gases leaving said otheroiftake thereby to control the heat absorbed by each of said fluidheaters in the said one offtake and said other oiftake passes.

11. In a steam generating unit having an associated furnace; an oiftakeadjacent one end of the furnace and another offtake adjacent the otherend of the furnace; means forming two passes for fthe ow offurnace-leaving gases therethrough, the rst of said passes beingconnected to the said yone oiftake and the second pass being connectedto the said other offtake; at least one fluid heater arranged in each ofsaid first and second passes; burner means located in the furnace wallsintermediate said two offtakes for there delivering into the furnace astream of combustible mixture creating a mass of high temperatureburning gas within the furnace interior; means for tilting said burnermeans to direct said stream of combustible mixture issuing therefromeither toward the fur- Vnaces said one offtake or toward the furnacessaid other offtake so as to bring the location of said mass of burninggas within Ithe furnace walls either closer to said one offtake and moreremote from the other offtake or closer to said other olftake and moreremote from said one oitake and, by reason of the direction given bysaid burner tilt to the velocity head inherent in said stream ofcombustible mixture to increase the gas pressure adjacent the particularofftake towards which the burner means is tilted Iand thereby cause thegas iiow through 'that oitake correspondingly to increase; and steamgenerating tubes lining the walls of said furnace for absorption of heatfrom said mass of high temperature gas, the quantity of heat so absorbedby said walllining tubes varying with rthe location off said hightemperature gas mass within the furnace along the length thereof betweensaid one end offtake and said other end oiftake lwhereby the aforesaidtilting of said burner means alters the total heat leaving both the oneand the other furnace offtakes and varies both the quantity and thetemperature of the gases leaving said one 01T- take and of the gasesleaving said other oitake thereby to control the heat absorbed by eachof said iiuid heaters in the said one oiftake and said other oiTta-kepasses.

JOSEPH A. LACE'RENZA.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,975,268 ,Grady Oct. 2, 19342,100,190 Jackson Nov. 23, 1937 '2,109,840 Gordon Mar. 1, 1938 2,431,177Iager et al Nov. 18, 1947

